(a) Field of the Invention
The present invention relates to a liquid crystal display apparatus and a method for driving the same, and more specifically, an apparatus and a method for driving the liquid crystal display with reduced crosstalk and distortion.
(b) Description of the Related Art
Liquid crystal display is widely used for flat panel display devices in many applications. Generally, the liquid crystal display has two substrates with electrodes, and a liquid crystal layer interposed between the two substrates. Each of the two substrates is sealed by a sealer while being spaced apart from each other by spacers. A voltage is applied to the electrodes so that the liquid crystal molecules in the liquid crystal layer are re-oriented to thereby control an amount of light transmission through the liquid crystal layer. Thin film transistors are provided at one of the substrates to control the signals transmitted to the electrodes.
It is known that the operations of a liquid crystal display depend at least in part on the turning on and off of electric fields applied to liquid crystals. Crosstalk is the interfering effect from signals or noise generated by the turning on and off of the electric field or transmitted signals.
In a liquid crystal display, crosstalk is also generated from the charging and discharging of pixels, which is proportional to the difference between an input gray voltage at a data line and a common electrode voltage. The distortion of the common electrode voltage may prevent pixels from reducing a desired gray voltage.
The distortion of the common electrode voltage is usually caused by a parasitic capacitance between a data line (horizontal resolution×3) in the liquid crystal display and a common electrode in the upper liquid crystal display panel. More specifically, the distortion typically occurs when the gray voltage at the data line rises or falls and the common electrode voltage is coupled to the rising or falling voltage. Uncontrolled crosstalk or distortion adversely affects the picture quality of the liquid crystal display. FIG. 1 shows a waveform of a signal having crosstalk. Referring to FIG. 1, the pixel charging state is determined in proportion to the area related to the difference between the gray voltage level and the common electrode voltage level, with area A having larger amplitude of the gray voltage waveform as compared to area B. This difference in areas A and B causes variations in the charging rate, such as in the intermediate gray voltage. Accordingly, a need exists for a liquid crystal display having an anti-crosstalk function to thereby secure a constant charging rate of a pixel of the liquid crystal display.